Lens module

ABSTRACT

A lens module includes first to seventh lenses each having refractive power and sequentially disposed in numerical order from the first lens to the seventh lens starting from an object side of the lens module, wherein each of the first and second lenses has a meniscus shape and an image-side surface that is convex, and the seventh lens has one or more inflection points on an image-side surface thereof.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Continuation of U.S. patent application Ser. No.16/860,473 filed on Apr. 28, 2020, which is a Continuation of U.S.patent application Ser. No. 15/890,529 filed on Feb. 7, 2018, now U.S.Pat. No. 10,678,024 issued on Jun. 9, 2020, which is a Continuation ofU.S. patent application Ser. No. 14/943,256 filed on Nov. 17, 2015, nowU.S. Pat. No. 9,927,596 issued on Mar. 27, 2018, which claims thebenefit under 35 USC § 119(a) of Korean Patent Application No.10-2014-0177445 filed on Dec. 10, 2014, in the Korean IntellectualProperty Office, the entire disclosures of which are incorporated hereinby reference for all purposes.

BACKGROUND 1. Field

This application relates to a lens module having an optical systemincluding seven lenses.

2. Description of Related Art

A lens module mounted in a camera of a mobile communications terminaltypically includes a plurality of lenses. For example, the lens modulemay include seven lenses to configure n optical system having a highresolution.

However, when the optical system having a high resolution is configuredusing the plurality of lenses as described above, a length (distancefrom an object-side surface of a first lens to an image plane) of theoptical system may be increased. In this case, it is difficult toinstall the lens module in a slim mobile communications terminal.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In one general aspect, a lens module includes first to seventh lenseseach having refractive power and sequentially disposed in numericalorder from the first lens to the seventh lens starting from an objectside of the lens module; wherein each of the first and second lenses hasa meniscus shape and an image-side surface that is convex; and theseventh lens has one or more inflection points on an image-side surfacethereof.

An object-side surface of the first lens may be concave.

An object-side surface of the second lens may be concave.

Both surfaces of the third lens may be convex.

The fourth lens may have a meniscus shape and an object-side surfacethat is convex.

The fifth lens has a meniscus shape and an image-side surface that isconvex.

The sixth lens may have a meniscus shape and an image-side surface thatis convex.

The seventh lens may have a meniscus shape and an object-side surfacethat is convex.

The image-side surface of the seventh lens may be concave.

At least five of the first to seventh lenses may be made of plastic.

In another general aspect, a lens module includes a first lens havingpositive refractive power, an object-side surface thereof being concave;a second lens having negative refractive power; a third lens havingpositive refractive power; a fourth lens having negative refractivepower; a fifth lens having refractive power; a sixth lens havingrefractive power; and a seventh lens having negative refractive powerand having one or more inflection points on an image-side surfacethereof; wherein the first to seventh lenses are sequentially disposedin numerical order from the first lens to the seventh lens starting froman object side of the lens module.

The fifth lens may have negative refractive power.

The sixth lens may have positive refractive power.

The lens module may further include a stop disposed between the thirdand fourth lenses.

In the lens module, 80°<FOV may be satisfied, where FOV is a field ofview of an optical system including the first to seventh lenses.

In the lens module, d2/d3<0.2 may be satisfied, where d2 is a distancefrom an image-side surface of the first lens to an object-side surfaceof the second lens, and d3 is a thickness of the second lens.

In another aspect, a lens module includes first to seventh lenses eachhaving refractive power and sequentially disposed in numerical orderfrom the first lens to the seventh lens starting from an object side ofthe lens module; wherein effective radii of surfaces of the first tothird lenses strictly decrease in order from an object-side surface ofthe first lens to an image-side surface of the third lens; and effectiveradii of surfaces of the fourth to seventh lenses strictly increase inorder from an object-side surface of the fourth lens to an image-sidesurface of the seventh lens.

The first, third, and sixth lens may have positive refractive power; andthe second, fourth, fifth, and seventh lenses may have negativerefractive power.

The first, second, fourth, fifth, and sixth lenses may have a meniscusshape; the third lens may not have a meniscus shape; and the seventhlens may have one or more inflection points on an image-side surfacethereof.

An image-side surface of each of the first, second, fifth, sixth, andseventh lenses may be concave; both surfaces of the third lens may beconvex; and an image-side surface of the fourth lens may be convex.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view of a first example of a lens module.

FIG. 2 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 1 .

FIG. 3 illustrates graphs including curves representing modulationtransfer function (MTF) characteristics of the lens module illustratedin FIG. 1 .

FIG. 4 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 1 .

FIG. 5 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 1 .

FIG. 6 is a view of a second example of a lens module.

FIG. 7 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 6 .

FIG. 8 illustrates graphs including curves representing MTFcharacteristics of the lens module illustrated in FIG. 6 .

FIG. 9 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 6 .

FIG. 10 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 6 .

FIG. 11 is a view of a third example of a lens module.

FIG. 12 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 11 .

FIG. 13 illustrates graphs including curves representing MTFcharacteristics of the lens module illustrated in FIG. 11 .

FIG. 14 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 11 .

FIG. 15 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 11 .

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

In this application, a first lens refers to a lens closest to an object(or a subject), while a seventh lens refers to a lens closest to animage plane (or an image sensor). Further, a first surface of each lensrefers to a surface thereof closest to an object (or a subject), and asecond surface of each lens refers to a surface thereof closest to animage plane (or an image sensor). Further, all of radii of curvature,thicknesses, OALs (optical axis distances from a first surface of thefirst lens to the image plane), SLs (distances from a stop to an imageplane), IMGHs (image heights), and BFLs (back focus lengths) of thelenses, an overall focal length of an optical system, and a focal lengthof each lens are expressed in millimeters (mm). Additionally,thicknesses of lenses, gaps between the lenses, OALs, and SLs aredistances measured based on an optical axis of the lenses. Further, in adescription for shapes of the lenses, a statement that one surface of alens is convex means that an optical axis portion of a correspondingsurface is convex, and a statement that one surface of a lens is concavemeans that an optical axis portion of a corresponding surface isconcave. Therefore, although it may be stated that one surface of a lensis convex, an edge portion of the lens may be concave. Likewise,although it is may be stated that one surface of a lens is concave, anedge portion of the lens may be convex.

A lens module includes an optical system including a plurality oflenses. For example, the optical system of the lens module may includeseven lenses having refractive power. However, the lens module is notlimited to only including the seven lenses. For example, the lens modulemay include other components that do not have refractive power. As anexample, the lens module may include a stop controlling an amount oflight. As another example, the lens module may further include aninfrared cut-off filter filtering infrared light. As another example,the lens module may further include an image sensor (that is, an imagingdevice) converting an image of a subject incident thereon through theoptical system into electrical signals. As another example, the lensmodule may further include a gap maintaining member adjusting a gapbetween lenses.

First to seventh lenses may be formed of materials having a refractiveindex different from that of air. For example, the first to seventhlenses may be formed of plastic or glass. At least one of the first toseventh lenses may have an aspheric shape. As an example, only theseventh lens of the first to seventh lenses may have an aspheric shape.As another example, at least one surface of all of the first to seventhlenses may be aspherical. Here, the aspherical surface of each lens maybe represented by the following Equation 1:

$\begin{matrix}{Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {Fr}^{14} + {Gr}^{16} + {Hr}^{18} + {Jr}^{20}}} & (1)\end{matrix}$

Here, c is an inverse of a radius of curvature of a corresponding lens,k is a conic constant, and r is a distance from a certain point on anaspherical surface to an optical axis in a direction perpendicular tothe optical axis. In addition, constants A to J are respectively 4thorder to 20th order aspheric coefficients. In addition, Z is a distancebetween the certain point on the aspherical surface at the distance rand a tangential plane meeting the apex of the aspherical surface of thelens.

The optical system of the lens module may have a wide field of view(FOV) of 80° or more. Therefore, the lens module may easily image a widebackground or object.

The lens module includes the first to seventh lenses. In addition, thelens module includes include a filter and an image sensor. Next, theabove-mentioned components will be described.

The first lens may have refractive power. For example, the first lensmay have positive refractive power.

The first lens may have a meniscus shape. As an example, the first lensmay have a meniscus shape of which a first surface (object-side surface)is convex and a second surface (image-side surface) is concave.

The first lens may have an aspherical surface. For example, bothsurfaces of the first lens may be aspherical. The first lens may beformed of a material having high light transmissivity and excellentworkability. For example, the first lens may be formed of plastic.However, a material of the first lens is not limited to plastic. Forexample, the first lens may be formed of glass.

The first lens may be formed of a material having a high refractiveindex. For example, the first lens may be formed of a material having arefractive index of 1.70 or more. The first lens formed of this materialmay easily refract light even while having a small curvature. Therefore,the first lens formed of this material may be easily manufactured and beadvantageous in lowering a defect rate depending on a manufacturingtolerance. In addition, the first lens formed of this material maydecrease a distance between lenses, and thus it may be advantageous inminiaturizing the lens module.

The second lens may have refractive power. For example, the second lensmay have negative refractive power.

The second lens may have a meniscus shape. For example, the second lensmay have a meniscus shape of which a first surface is concave and asecond surface is convex.

The second lens may have an aspherical surface. For example, animage-side surface of the second lens may be aspherical. The second lensmay be formed of a material having high light transmissivity andexcellent workability. For example, the second lens may be formed ofplastic. However, a material of the second lens is not limited toplastic. For example, the second lens may be formed of glass.

The second lens may be formed of a material having a high refractiveindex. For example, the second lens may be formed of a material having arefractive index of 1.60 or more (in this case, the second lens may havean Abbe number of 30 or less). The second lens formed of this materialmay easily refract light even while having a small curvature. Therefore,the second lens formed of this material may be easily manufactured andbe advantageous in lowering a defect rate depending on a manufacturingtolerance. In addition, the second lens formed of this material maydecrease a distance between lenses, and thus it may be advantageous inminiaturizing the lens module.

The third lens may have refractive power. For example, the third lensmay have positive refractive power.

One surface of the third lens may be convex. As an example, a firstsurface of the third lens may be convex. As another example, a secondsurface of the third lens may be convex. As another example, bothsurfaces of the third lens may be convex.

The third lens may have an aspherical surface. For example, bothsurfaces of the third lens may be aspherical. The third lens may beformed of a material having high light transmissivity and excellentworkability. For example, the third lens may be formed of plastic.However, a material of the third lens is not limited to plastic. Forexample, the third lens may be formed of glass.

The fourth lens may have refractive power. For example, the fourth lensmay have negative refractive power.

The fourth lens may have a meniscus shape. For example, the fourth lensmay have a meniscus shape of which a first surface is convex and asecond surface is concave.

The fourth lens may have an aspherical surface. For example, bothsurfaces of the fourth lens may be aspherical. The fourth lens may beformed of a material having high light transmissivity and excellentworkability. For example, the fourth lens may be formed of plastic.However, a material of the fourth lens is not limited to plastic. Forexample, the fourth lens may be formed of glass.

The fourth lens may be formed of a material having a high refractiveindex. For example, the fourth lens may be formed of a material having arefractive index of 1.60 or more (in this case, the fourth lens may havean Abbe number of 30 or less). The fourth lens formed of this materialmay easily refract light even while having a small curvature. Therefore,the fourth lens formed of this material may be easily manufactured andbe advantageous in lowering a defective rate depending on amanufacturing tolerance. In addition, the fourth lens formed of thismaterial may decrease a distance between lenses, and thus it may beadvantageous in miniaturizing the lens module.

The fifth lens may have refractive power. For example, the fifth lensmay have negative refractive power.

The fifth lens may have a meniscus shape. For example, the fifth lensmay have a meniscus shape of which a first surface is concave and asecond surface is convex.

The fifth lens may have an aspherical surface. For example, bothsurfaces of the fifth lens may be aspherical. The fifth lens may beformed of a material having high light transmissivity and excellentworkability. For example, the fifth lens may be formed of plastic.However, a material of the fifth lens is not limited to plastic. Forexample, the fifth lens may be formed of glass.

The fifth lens may be formed of a material having a high refractiveindex. For example, the fifth lens may be formed of a material having arefractive index of 1.60 or more (in this case, the fifth lens may havean Abbe number of 30 or less). The fifth lens formed of this materialmay easily refract light even while having a small curvature. Therefore,the fifth lens formed of this material may be easily manufactured and beadvantageous in lowering a defective rate depending on a manufacturingtolerance. In addition, the fifth lens formed of this material maydecrease a distance between lenses, and thus it may be advantageous inminiaturizing the lens module.

The sixth lens may have refractive power. For example, the sixth lensmay have positive refractive power.

The sixth lens may have a meniscus shape. For example, the sixth lensmay have a meniscus shape of which a first surface is concave and asecond surface is convex.

The sixth lens may have an aspherical surface. For example, bothsurfaces of the sixth lens may be aspherical. The sixth lens may beformed of a material having high light transmissivity and highworkability. For example, the sixth lens may be formed of plastic.However, a material of the sixth lens is not limited to plastic. Forexample, the sixth lens may be formed of glass.

The seventh lens may have refractive power. For example, the seventhlens may have negative refractive power.

One or more inflection points may be formed on at least one of anobject-side surface and an image-side surface of the seventh lens. As anexample, a first surface of the seventh lens may be convex at the centerof an optical axis, but may be concave in the vicinity of the opticalaxis. As another example, a second surface of the seventh lens may beconcave at the center of the optical axis, but may be convex in thevicinity of the optical axis.

The seventh lens may have an aspherical surface. For example, bothsurfaces of the seventh lens may be aspherical. The seventh lens may beformed of a material having high light transmissivity and excellentworkability. For example, the seventh lens may be formed of plastic.However, a material of the seventh lens is not limited to plastic. Forexample, the seventh lens may be formed of glass.

The filter may filter a partial wavelength from incident light incidentthrough the first to seventh lenses. For example, the filter may be aninfrared cut-off filter filtering an infrared wavelength of the incidentlight. The filter may be formed of plastic or glass and have an Abbenumber of 60 or more.

The image sensor may have a high resolution of 1300 megapixels. Forexample, a unit size of the pixels of the image sensor may be 1.12 μm orless.

The lens module configured as described above may have a wide field ofview. For example, the lens module may have a field of view of 80° ormore. In addition, the lens module may have a relatively short length.For example, an overall length TTL (a distance from the object-sidesurface of the first lens to the image plane) of the optical system ofthe lens module may be 5.80 mm or less. Therefore, the lens module maybe advantageously miniaturized.

The lens module may satisfy the following Conditional Expression:

80°<FOV

Here, FOV is a field of view of the optical system including the firstto seventh lenses.

The lens module may satisfy at least one of the following ConditionalExpressions:

d2<0.5 mm

d2/d3<0.2

Here, d2 is a distance from an image-side surface of the first lens toan object-side surface of the second lens, and d3 is a thickness of thesecond lens.

The lens module may satisfy at least one of the following ConditionalExpressions:

V4<30

V5<30

(V4+V5)/30<1.8

Here, V4 is an Abbe number of the fourth lens, and V5 is an Abbe numberof the fifth lens.

The above Conditional Expressions are conditions for selecting materialsof the fourth and fifth lenses. For example, in a case in which theabove Conditional Expressions are satisfied, the fourth and fifth lensesare advantageous in improving chromatic aberration.

The lens module may satisfy at least one of the following ConditionalExpressions:

d7<0.26 mm

d7/d8<0.5

Here, d7 is a thickness of the fourth lens, and d8 is a distance from animage-side surface of the fourth lens to an object-side surface of thefifth lens.

FIG. 1 is a view of a first example of a lens module.

A lens module 100 includes an optical system including a first lens 110,a second lens 120, a third lens 130, a fourth lens 140, a fifth lens150, a sixth lens 160, and a seventh lens 170. In addition, the lensmodule 100 further includes an infrared cut-off filter 80 and an imagesensor 90. Further, the lens module 100 includes a stop (ST). In thisexample, the stop is disposed between the third lens 130 and the fourthlens 140.

In this example, the first lens 110 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The second lens 120 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The third lens 130 has positive refractive power, andan object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 140 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The fifth lens 150 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 160 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The seventh lens 170 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the seventh lens 170 has an asphericshape in which inflection points are formed on an object-side surfaceand an image-side surface thereof, respectively.

In this example, all of the first lens 110, the third lens 130, and thesixth lens 160 have positive refractive power. Among these lenses, thethird lens 130 has the strongest refractive power, and the first lens110 has the weakest refractive power.

In this example, all of the second lens 120, the fourth lens 140, thefifth lens 150, and the seventh lens 170 have negative refractive power.Among these lenses, the fourth lens 140 has the strongest refractivepower, and the seventh lens 170 has the weakest refractive power.

FIG. 2 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 1 .

FIG. 3 illustrates graphs including curves representing modulationtransfer function (MTF) characteristics of the lens module illustratedin FIG. 1 .

FIG. 4 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 1 . In FIG. 4 , Surface Nos. S1 and S2indicate the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4indicate the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S14 indicate the first and second surfaces of thethird to seventh lenses, respectively. In addition, Surface Nos. S15 andS16 indicate first and second surfaces of the infrared cut-off filter.

In this example, effective radii of the lenses gradually decrease fromthe object-side surface of the first lens to the image-side surface ofthe third lens, and gradually increase from the object-side surface ofthe fourth lens to the image-side surface of the seventh lens, asillustrated in FIG. 4 . That is, as can be seen from FIG. 4 , theeffective radii of the surfaces of the first lens to the third lensstrictly decrease from the object-side surface of the first lens to theimage-side surface of the third lens, and the effective radii of thesurfaces of the fourth lens to the seventh lens strictly increase fromthe object-side surface of the fourth lens to the image-side surface ofthe seventh lens. In this example, the effective radius of theobject-side surface of the fourth lens is greater than the effectiveradius of the image-side surface of the third lens. In a strictlydecreasing sequence of values, each value is less than the precedingvalue in the sequence. In a strictly increasing sequence of values, eachvalue is greater than the preceding value in the sequence.

FIG. 5 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 1 . In FIGS. 5 , S1 toS14 indicate Surface Nos. of respective surfaces of the first to seventhlenses, and k and A to J indicate conic constants (k) and asphericcoefficients (A to J) of respective surfaces of the first to seventhlenses.

FIG. 6 is a view of a second example of a lens module.

A lens module 200 includes an optical system including a first lens 210,a second lens 220, a third lens 230, a fourth lens 240, a fifth lens250, a sixth lens 260, and a seventh lens 270. In addition, the lensmodule 200 further includes an infrared cut-off filter 80 and an imagesensor 90. Further, the lens module 200 may include a stop (ST). In thisexample, the stop is disposed between the third lens 230 and the fourthlens 240.

In this example, the first lens 210 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The second lens 220 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The third lens 230 has positive refractive power, andan object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 240 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The fifth lens 250 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 260 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The seventh lens 270 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the seventh lens 270 has an asphericshape in which inflection points are formed on an object-side surfaceand an image-side surface thereof, respectively.

In this example, all of the first lens 210, the third lens 230, and thesixth lens 260 have positive refractive power. Among these lenses, thethird lens 230 has the strongest refractive power, and the first lens210 has the weakest refractive power.

In this example, all of the second lens 220, the fourth lens 240, thefifth lens 250, and the seventh lens 270 have negative refractive power.Among these lenses, the fourth lens 240 has the strongest refractivepower, and the seventh lens 270 has the weakest refractive power.

FIG. 7 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 6 .

FIG. 8 illustrates graphs including curves representing MTFcharacteristics of the lens module illustrated in FIG. 6 .

FIG. 9 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 6 . In FIG. 9 , Surface Nos. S1 and S2indicate the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4indicate the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S14 indicate the first and second surfaces of thethird to seventh lenses, respectively. In addition, Surface Nos. S15 andS16 indicate first and second surfaces of the infrared cut-off filter.

In this example, effective radii of the lenses gradually decrease fromthe object-side surface of the first lens to the image-side surface ofthe third lens, and gradually increase from the object-side surface ofthe fourth lens to the image-side surface of the seventh lens, asillustrated in FIG. 9 . That is, as can be seen from FIG. 9 , theeffective radii of the surfaces of the first lens to the third lensstrictly decrease from the object-side surface of the first lens to theimage-side surface of the third lens, and the effective radii of thesurfaces of the fourth lens to the seventh lens strictly increase fromthe object-side surface of the fourth lens to the image-side surface ofthe seventh lens. In this example, the effective radius of theobject-side surface of the fourth lens is greater than the effectiveradius of the image-side surface of the third lens.

FIG. 10 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 6 . In FIGS. 10 , S1to S14 indicate Surface Nos. of respective surfaces of the first toseventh lenses, and k and A to J indicate conic constants (k) andaspheric coefficients (A to J) of respective surfaces of the first toseventh lenses.

FIG. 11 is a view of a third example of a lens module.

A lens module 300 includes an optical system including a first lens 310,a second lens 320, a third lens 330, a fourth lens 340, a fifth lens350, a sixth lens 360, and a seventh lens 370. In addition, the lensmodule 300 further includes an infrared cut-off filter 80 and an imagesensor 90. Further, the lens module 300 includes a stop (ST). In thisexample, the stop is disposed in front of the third lens 330.

In this example, the first lens 310 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The second lens 320 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The third lens 330 has positive refractive power, andan object-side surface thereof is convex and an image-side surfacethereof is convex. The fourth lens 340 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. The fifth lens 350 has negative refractive power,and an object-side surface thereof is concave and an image-side surfacethereof is convex. The sixth lens 360 has positive refractive power, andan object-side surface thereof is concave and an image-side surfacethereof is convex. The seventh lens 370 has negative refractive power,and an object-side surface thereof is convex and an image-side surfacethereof is concave. In addition, the seventh lens 370 has an asphericshape in which inflection points are formed on an object-side surfaceand an image-side surface thereof, respectively.

In this example, all of the first lens 310, the third lens 330, and thesixth lens 360 have positive refractive power. Among these lenses, thethird lens 330 has the strongest refractive power, and the first lens310 has the weakest refractive power.

in this example, all of the second lens 320, the fourth lens 340, thefifth lens 350, and the seventh lens 370 have negative refractive power.Among these lenses, the fourth lens 340 has the strongest refractivepower, and the seventh lens 370 has the weakest refractive power.

FIG. 12 illustrates graphs including curves representing aberrationcharacteristics of the lens module illustrated in FIG. 11 .

FIG. 13 illustrates graphs including curves representing MTFcharacteristics of the lens module illustrated in FIG. 11 .

FIG. 14 is a table listing characteristics of the lenses of the lensmodule illustrated in FIG. 11 . In FIG. 14 , Surface Nos. S1 and S2indicate the first surface (object-side surface) and the second surface(image-side surface) of the first lens, and Surface Nos. S3 and S4indicate the first and second surfaces of the second lens. Similarly,Surface Nos. S5 to S14 indicate the first and second surfaces of thethird to seventh lenses, respectively. In addition, Surface Nos. S15 andS16 indicate first and second surfaces of the infrared cut-off filter.

In this example, effective radii of the lenses gradually decrease fromthe object-side surface of the first lens to the image-side surface ofthe third lens, and gradually increase from the object-side surface ofthe fourth lens to the image-side surface of the seventh lens, asillustrated in FIG. 14 . That is, as can be seen from FIG. 14 , theeffective radii of the surfaces of the first lens to the third lensstrictly decrease from the object-side surface of the first lens to theimage-side surface of the third lens, and the effective radii of thesurfaces of the fourth lens to the seventh lens strictly increase fromthe object-side surface of the fourth lens to the image-side surface ofthe seventh lens. In this example, the effective radius of theobject-side surface of the fourth lens is greater than the effectiveradius of the image-side surface of the third lens.

FIG. 15 is a table listing conic constants and aspheric coefficients ofthe lenses of the lens module illustrated in FIG. 11 . In FIGS. 15 , S1to S14 indicate Surface Nos. of respective surfaces of the first toseventh lenses, and k and A to J indicate conic constants (k) andaspheric coefficients (A to J) of respective surfaces of the first toseventh lenses.

The following Table 1 lists optical characteristics of the lens modulesof the first to third examples. The lens module has an overall focallength (f) of 3.5 to 3.7. A focal length (f1) of the first lens isdetermined to be in a range of 14.0 to 29.0. A focal length (f2) of thesecond lens is determined to be in a range of −14.0 to −11.0. A focallength (f3) of the third lens is determined to be in a range of 2.4 to2.7. A focal length (f4) of the fourth lens is determined to be in arange of −21.0 to −10.0. A focal length (f5) of the fifth lens isdetermined to be in a range of −8.0 to −4.0. A focal length (f6) of thesixth lens is determined to be in a range of 2.5 to 3.3. A focal length(f7) of the seventh lens is determined to be in a range of −3.0 to −2.6.

In the lens module, an overall length (TTL) of the optical system isdetermined to be in a range of 5.1 to 5.8. An overall length (SL) of thestop to the image plane is determined to be in a range of 4.1 to 4.6. Afield of view (FOV) of the lens module is 80° or more. A f-number of thelens module is 2.2 or less.

TABLE 1 First Second Third Remarks Example Example Example f 3.639 3.6333.610 f1 26.145 27.808 14.779 f2 −12.230 −12.978 −12.308 f3 2.597 2.5852.534 f4 −19.490 −18.629 −11.205 f5 −5.008 −4.976 −6.701 f6 2.648 2.6733.173 f7 −2.838 −2.798 −2.718 TTL 5.700 5.700 5.200 SL 4.180 4.200 4.500FOV 82.0 82.0 82.0 f-number 2.11 2.11 2.10

The following Table 2 lists values of Conditional Expressions of thelens modules of the first to third examples.

TABLE 2 Conditional First Second Third Expressions Example ExampleExample d2/d3 0.1794 0.1678 0.1915 (V4 + V5)/30 1.5580 1.5580 1.5580d7/d8 0.3530 0.3453 0.3194

As seen in Table 2, the lens modules of the first to third examplessatisfy all of the Conditional Expressions.

The examples described above enable the optical system to have a highresolution.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner, and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A lens module comprising: a first lens havingpositive refractive power; a second lens having a refractive power; athird lens having positive refractive power; a fourth lens havingnegative refractive power; a fifth lens having a concave object-sidesurface; a sixth lens having a refractive power; and a seventh lenshaving a convex object-side surface, wherein the first to seventh lensesare sequentially disposed in numerical order from an object side of thelens module, wherein a radius of curvature of an object-side surface ofthe fourth lens is greater than a radius of curvature of an object-sidesurface of the second lens.
 2. The lens module of claim 1, wherein thesecond lens has negative refractive power.
 3. The lens module of claim1, wherein the sixth lens has positive refractive power.
 4. The lensmodule of claim 1, wherein the seventh lens has negative refractivepower.
 5. The lens module of claim 1, wherein the third lens has aconvex image-side surface.
 6. The lens module of claim 1, wherein thefourth lens has a convex object-side surface.
 7. The lens module ofclaim 1, wherein the fourth lens has a concave image-side surface. 8.The lens module of claim 1, wherein the fifth lens has a conveximage-side surface.
 9. The lens module of claim 1, wherein the seventhlens has a concave image-side surface.
 10. A lens module comprising: afirst lens having positive refractive power; a second lens having arefractive power; a third lens having positive refractive power; afourth lens having negative refractive power; a fifth lens having aconcave object-side surface; a sixth lens having a refractive power; anda seventh lens having a convex object-side surface, wherein the first toseventh lenses are sequentially disposed in numerical order from anobject side of the lens module, wherein a radius of curvature of animage-side surface of the sixth lens is greater than a radius ofcurvature of an object-side surface of the sixth lens.
 11. The lensmodule of claim 10, wherein an F number of the lens module is 2.2 orless.
 12. The lens module of claim 10, wherein d2/d3<0.2, where d2 is adistance from an image-side surface of the first lens to an object-sidesurface of the second lens and d3 is a thickness along an optical axisof the second lens.
 13. The lens module of claim 10, wherein V4<30,where V4 is an Abbe number of the fourth lens.
 14. The lens module ofclaim 10, wherein a radius of curvature of an object-side surface of thefourth lens is greater than a radius of curvature of an object-sidesurface of the second lens.
 15. The lens module of claim 10, wherein athickness along an optical axis of the fifth lens is greater than athickness along an optical axis of the fourth lens.